This study determined the prevalence and toxin profile of Bacillus cereus and Bacillus thuringiensis in doenjang, a fermented soybean food, made using both traditional and commercial methods. The 51 doenjang samples tested were broadly contaminated with B. cereus; in contrast, only one sample was positive for B. thuringiensis. All B. cereus isolates from doenjang were positive for diarrheal toxin genes. The frequencies of nheABC and hblACD in traditional samples were 22.7 and 0%, respectively, whereas 5.1 and 5.1% of B. cereus isolates from commercial samples possessed nheABC and hblACD, respectively. The detection rate of ces gene was 10.8%. The predominant toxin profile among isolates from enterotoxigenic B. cereus in doenjang was profile 4 (entFM-bceT-cytK). The major enterotoxin genes in emetic B. cereus were cytK, entFM, and nheA genes. The B. thuringiensis isolate was of the diarrheagenic type. These results provide a better understanding of the epidemiology of the enterotoxigenic and emetic B. cereus groups in Korean fermented soybean products.

Changes in the volatile components in Fuji apples were investigated by the analysis of intact apples using headspace solid‐phase microextraction–gas chromatography–mass spectrometry to assess their quality during long‐term storage at 4°C (3, 6, and 9 months). Three alcohols and 28 esters were identified, and the feeding of precursor alcohols (e.g., butanol, hexanol, and 2‐methylbutanol) resulted in significantly increased amounts of eight esters. Among these esters, the peak area ratios (PARs) of butyl acetate, butyl butanoate, butyl 2‐methylbutanotate, or 2‐methylbutyl acetate to the eight esters were highly correlated with those of their precursor alcohols to the total alcohol content (R2 ≥ .9253). In addition, the PAR of precursor alcohols to the total alcohol content, as well as the PAR of these esters to the eight esters, significantly increased during storage at 4°C (p < .01). Therefore, it is concluded that PARs can be used as quality indicators for Fuji apples. Practical applications Quality assessment is crucial in the food industry to maintain food quality. An accurate, rapid method must be available for an assessment of quality. In addition, the identification of reliable biomarkers is imperative for quality assessment. Because of their versatility, volatile compounds in foods can provide considerable information about the quality of foods. In this study, volatile compounds in Fuji apples served as good quality indicators, and these apples were nondestructively analyzed without sample treatment. In addition, multiple volatile indicators were identified and validated. The results suggested that the volatile compounds analyzed by this nondestructive method can serve as indicators for the rapid, robust assessment of the quality of Fuji apples in the agricultural industry.

This study investigated the effect of heat treatments on the quality characteristics of fresh-cut 'Romaine' lettuce by treating in hot water (45, 50, and 55℃) for 2 minutes. Sensory properties, respiration rate, ethylene production, microbial growth, browning index, total phenolics (TP), vitamin C, and antioxidant properties (DPPH, ABTS, and FRAP assays) of samples were evaluated after 5 days at 5℃. All heat treatment conditions tested in this study did not affect the change in TP after storage. Treatment at 45℃ enhanced respiration rate and ethylene production wheres decreased vitamin C content and antioxidant activities. There was no significant difference in browning index at 45℃ treatment. The rapid tissue softening occurred when treated with 55℃ hot water for 2 minutes. The 50℃ heat treatments exhibited the best quality index including texture and color, and inhibited microbial growth and browning after storage. In addition, the 50℃ heat treatment showed the highest vitamin C content and antioxidant activities (DPPH, ABTS, FRAP assay) after storage. Therefore, the 50℃ heat treatment can be used to maintain quality and antioxidant property of fresh-cut 'Romain' lettuce.

This study was conducted to investigate the effect of mature stages on quality of Rafito tomatoes (Lycopersicon esculentum Mill.) during storage at low temperature. Tomatoes grown in greenhouse were harvested at three different mature stages (turning, pink, and red), packaged with a 30-μm-thick polyethylene film, and then stored at 5 and 10℃, respectively. The changes in firmness, soluble solids content (SSC), titratable acidity (TA), colour, lycopene content, decay, and chilling injury were measured on a weekly basis. After three weeks of storage, chilling injury and decay were found to have individually occurred at 5 and 10℃, respectively. As there was little change in quality at 5℃, it was concluded that red tomatoes could maintain their good quality for two weeks. The normal postharvest ripening was inhibited in the turning and pink tomatoes during storage at 5℃. The turning and pink tomatoes showed improved quality after two-week storage at 10℃. In particular, the turning fruits showed the highest firmness throughout the storage period. Furthermore, the red colour, SSC/TA, and lycopene content of the turning fruits reached the same levels as with the red fruits after two-week storage at 10℃. These results suggest that red tomatoes should be stored at 5℃ to inhibit decay, and that the optimum temperature for early-harvested tomato (turning and pink) is 10℃ for the ripening process after harvest.

This study was carried to investigate the physicochemical and microbiological characteristics of seasonal salted-Kimchi cabbage order to provide basic data for optimal salting and storage condition of seasonal Kimchi cabbage. Generally, fall season samples had slightly higher pH and acidity value than the other seasonal salted Kimchi cabbage. The soluble solids content of spring, summer, fall and winter samples were 5.95%, 6.18%, 6.29% and 7.76%, respectively. The salt content of all the seasonal salted Kimchi cabbage samples were insignificant. The number of microbial bacteria in the summer samples were generally much more significant than spring and winter samples. There was no significant difference in the color of seasonal salted Kimchi cabbage. As for the texture properties, the firmest samples in the surface rupture test were the spring samples (force: 4.92 kg), and the hardest samples in the puncture test were the summer samples (force: 11.71 kg). In the correlation analysis of the quality characteristics of seasonal samples, the soluble solids content and hardness of the seasonal salted Kimchi cabbage was significantly correlated at 1% significance level. Also, in the principal component analysis, F1 and F2 were shown to explain 27.28% and 35.59% of the total variance (62.87%), respectively. The hierarchical cluster analysis of the quality characteristics of seasonal samples, the samples were divided into three groups: spring cabbage group, summer cabbage group and fall and winter cabbage group,.